As the immune system fails, symptoms develop. Initially many of the symptoms are mild, but as the immune system deteriorates the symptoms worsen.

HIV infection can generally be broken down into four distinct stages: primary infection, clinically asymptomatic stage, symptomatic HIV infection, and progression from HIV to AIDS.

STAGE 1: Primary HIV infection

This stage of infection lasts for a few weeks and is often accompanied by a short flu-like illness. In about 20% of people the symptoms are serious enough to consult a doctor, but the diagnosis of HIV infection is frequently missed.

ADVERTISEMENTS:

During this stage there is a large amount of HIV in the peripheral blood and the immune system begins to respond to the virus by producing HIV antibodies and cytotoxic lymphocytes. This process is known as seroconversion. If an HIV antibody test is done before seroconversion is complete then it may not be positive.

STAGE 2: Clinically asymptomatic stage:

This stage lasts for an average of ten years and, as its name suggests, it is free from major symptoms, although there may be swollen glands. The level of HIV in the peripheral blood drops to very low levels but people remain infectious and HIV antibodies are detectable in the blood, so antibody tests will show a positive result.

Research has shown that HIV is not dormant during this stage, but is very active in the lymph nodes. A test which measures HIV RNA (HIV genetic material) is viral load test, and it has an important role in the treatment of HIV infection.

ADVERTISEMENTS:

STAGE 3: Symptomatic HIV infection:

Over time the immune system becomes severely damaged by HIV. The lymph nodes and tissues become damaged because of the years of activity.

HIV mutates and becomes more pathogenic. The body fails to keep up with replacing the T helper cells that are lost.

As the immune system fails, symptoms develop. Initially many of the symptoms are mild, but as the immune system deteriorates the symptoms worsen.

ADVERTISEMENTS:

Symptomatic HIV infection is mainly caused by the emergence of opportunistic infections and cancers that the immune system would normally prevent. This stage of HIV infection is often characterised by multi-system disease and infections can occur in almost all body systems.

STAGE 4: Progression from HIV to AIDS:

As the immune system becomes more and more damaged the illnesses that occur become more and more severe leading eventually to an AIDS diagnosis.

Symptoms of HIV vary according to the stage of the infection.

ADVERTISEMENTS:

WHO clinical staging of HIV disease in adults and adolescents (2006 revision)

In resource-poor communities, medical facilities are sometimes poorly equipped, and it is not possible to use CD4 and viral load test results to determine the right time to begin antiretroviral treatment.

The World Health Organisation (WHO) has therefore developed a staging system for HIV disease, based on clinical symptoms, which may be used to guide medical decision making.

Clinical Stage I:

ADVERTISEMENTS:

Asymptomatic

Persistent generalized lymphadenopathy

Clinical Stage II:

Moderate unexplained weight loss (under 10% of presumed or measured body weight)

ADVERTISEMENTS:

Recurrent respiratory tract infections (sinusitis, tonsillitis, otitis media, pharyngitis)

Herpes zoster

Angular chelitis

Recurrent oral ulceration

Papular pruritic eruptions

Seborrhoeic dermatitis

Fungal nail infections

Clinical Stage III:

Unexplained severe weight loss (over 10% of presumed or measured body weight)

Unexplained chronic diarrhoea for longer than one month

Unexplained persistent fever (intermittent or constant for longer than one month)

Persistent oral candidiasis

Oral hairy leukoplakia

Pulmonary tuberculosis

Severe bacterial infections (e.g. pneumonia, empyema, pyomyositis, bone or joint infection, meningitis, bacteraemia)

Acute necrotizing ulcerative stomatitis, gingivitis or periodontitis

Unexplained anaemia (below 8 g/dl), neutropenia (below 0.5 billion/1) and/ or chronic thrombocytopenia (below 50 billion/1)

Clinical Stage IV:

HIV wasting syndrome

Pneumocystis pneumonia

Recurrent severe bacterial pneumonia

Chronic herpes simplex infection (orolabial, genital or anorectal of more than one month’s duration or visceral at any site).

Oesophageal candidiasis (or candidiasis of trachea, bronchi or lungs).

Extrapulmonary tuberculosis.

Kaposi sarcoma.

Cytomegalovirus infection (retinitis or infection of other organs).

Central nervous system toxoplasmosis. HIV encephalopathy.

Extrapulmonary cryptococcosis including meningitis.

Disseminated non-tuberculous mycobacteria infection.

Progressive multifocal leukoencephalopathy.

Chronic cryptosporidiosis.

Chronic isosporiasis .

Disseminated mycosis (extrapulmonary histoplasmosis, coccidiomycosis).

Recurrent septicaemia (including non-typhoidal Salmonella).

Lymphoma (cerebral or B cell non-Hodgkin).

Invasive cervical carcinoma.

Atypical disseminated leishmaniasis.

Symptomatic HIV-associated nephropathy or HIV-associated cardiomyo­pathy.